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Changes in factor XI (plasma thromboplastin antecedent) levels during pregnancy

1973; Elsevier BV; Volume: 116; Issue: 8 Linguagem: Inglês

10.1016/0002-9378(73)90945-9

1097-6868

Louise Lang Phillips, Laura Rosanò, Valija Skrodelis,

Electrolyte and hormonal disorders

Factor XI (plasma thromboplastin antecedent [PTA]) has been determined in over 50 pregnant women, in 15 nonpregnant women, and in 12 women during the first 3 postpartum days. Values fell as the gestation progressed. There were no statistically significant differences between the nonpregnant women and the ones during the first trimester of pregnancy. However, the difference between the nonpregnant women and those in the second or third trimester of pregnancy was highly significant (p < 0.001). The correlation coefficient relating weeks of pregnancy with PTA level was also significant (p < 0.001). During the early postpartum period levels began to return toward normal. Although most coagulation factors increase during pregnancy, factor XIII (fibrin stabilizing factor) and now factor XI have been shown to decrease. It may be that the lower levels of these two substances help to counteract the trend toward a “hypercoagulable” state in pregnancy and to minimize thrombotic episodes during the antepartum period in the usual obstetric patient.